Measured-service telephone system



s. B. WILLIAMSET AL MEASURED SERVICE TELEPHONE SYSTEM 5 Sheets-Sheet 1 Filed August 19, 1924 7/7 vex? 70/3. Jamaal 5. W////d/775 Oct. 19 1926. 1,603,655

- s. B. WILLIAMS ET AL MEASURED SERVICE TELEPHONE SYSTEM Filed August 19, 1924 3 Sheets-Shoat 2 hvenfarr: Jamue/ 5 flW/fams [0/ J. G/Awn Oct. 19 1926.

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iii i il'i EB S SAMUEL B. WILLIAMS, ornnoonnynunnw YORK, AND EARL S. GIBSON, OF EIDGE "WOGD;v NEJJ JERSEY, ASSIGNOIRS TO ELECTRIC COMPANY, IN C QBPO RATED, OF NEW YORK, N. Y A COEPEI-IRAJZTION ()1? NEW YORK.

MEASURED-SERVICE TELZEPIEEGIIE Application filed August 19.

This invention relates to telephone exchange systems iii-general, and-more particulai'ly to such systeins wherein connections between telephone lines are conipl'eted and registered bymeans of automatic switching apparatus.

In telephone systems where connections are completed under control of impulses transmitted by a calling subscriber and recorded on a register sender, means are gen erally provided for preparing to charge the calling subscriber, in the event of the sue cess'tul completion of a call, immediately after response by the called subscriber.

In the case of individual lines terminating in an oi'fi ceeach message register-is associated with, and is individual to a subscribersline, and the registering of calls may be accomplished in substantially the same manner as that shown and described in the appli'eation'oi'i S. B. VVilliams, Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331,'graiited Dec. 2, 1924, wherein each subscribers line is shown as having access to a group of district selector trunks, by means of coordinate line switches. With each district selector trunk taken for use. there is associated certain mechanism which is operated upon the successful-establishment ot a connection from a calling line. toa called line. This mechanism having been prepared during the establishment'ot the connection is rendered effective upon the disruption thereof to close. an operating circuit for the message register associated with the calling subscribers line.

In the case of two party lines, that is to say where there are two message registers associated with the same line, it is necessary that some discriminating. condition exist when a call is initiated by one or the other of the subscribers served by thisline, in or der that the proper calling subscriber may be charged upon the completion of a successful call.

One manner of accomplishing this special tip conductor o1 the calling linethrough the call bell at one of!the'substationswhen .the subscribefis receiveris cit theiswitchhook. iowever, the condition might arise wherein the conductors of a party line" would he accidentally grounded, thus resultingiin the placing of a false condition 'onthe'linexe "a signal is given to an attendant. tliQCllSCOIlIiQCtlOH of the test relay vfrom the 1324-. Serial No. 732,817.

gard'l'ess of which of the two parties had iiiitiated the call. It is necessary, therefore, that some means be-pr'ovided' for detecting this false condition prior'to the operation ot the message register in order to forestall a fal e charging of the call.

It is an object of this'invention, therefore, to provide for the proper registering of calls initiated on party lines.

This object isobtained:by'providing a special party test relay associated with each district selector taken fo'r 'use. This test relay is, during the establishment ofa con nection, first energized over a local. circuit and at a later stage in the progress of the connection this'sanie test relay in its operated condition is applied to the conduc tors of-the call'i'ng'line-to test i'oi the presenccor absence of discriminating condition thereon. Should party No. 2 have initiated the call, a discriminating ground will be found upon the line and the test ielay will remain energized for an interval (as determined by a time measuring mechanism) to operate a party recordii'ig relay, after which the'test re lay is again released. Should the test relay remain operated longer than the period determined by the time measuring mechanism, Prior to calling line a check is made ofthe operating characteristics thereof as will be described in detail liereiiiatter. 4

Should, however party No. 1 have initiated the call no discriminating ground would order to determine the operation of the V proper message register; condition is to place ground potential entire 4 A feature of the invention reiates to an improved i'neans-for' deterininiiig a standard 'or'unstandard'condition of a calling line for the purpose 'ofcorrectly registering the calls initiated-thereon A further feature of'the invention relates to a partytest relay'which is applied to the calling linein an operated condition" to de termine the presence or absence of unstandard conditions and also for the purpose of responding to a discriminating condition on said calling line.

lVhile it has been chosen to illustrate the invention as applied to a telephone system wherein switches of the coordinate type are employed, it is understood that the invention in its broad aspects is not to be confined to this particular kind of system since it may be equally well applied to so-ealled power drive systems and in general to any system wherein selective operation of party line message registers is required.

The invention is an improvement on the call charging system disclosed in the application of D. M. Tagg'art and F. J. Scudder Serial No. 431,141, filed December 16, 1920, Patent No. 1,513,351, granted Oct. 28, 1924, wherein switches of the power driven type are shown. The invention disclosed herein however, is shown as applied to a telephone system of the general character disclosed in the application. of S. B. lVilliams Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331, to which reference may be had for a detailed description of the construction and operation of the several switches and controlling mechanisms shown in the drawings.

Figs. 1, 2 and 3 of the drawing when arranged with Fig. 2 to the right of Fig. 1, and Fig. 3 to the right of Fig. 2 show, partly in schematic form and partly in detail, sufficient portions of a telephone system embodying the features of the invention toenable one to obtain a complete understanding thereof.

Fig. 1 shows one of a number of telephone lines accommodating two subscribers substations. To the right of Fig. 1 is also shown a line switch'of the coordinate type. The portion of this figure included in the rectangle is intended to represent a master switch for controlling the selective operation of the line switch. In the lower left hand portion of this figure are shown two subscribers sta tions with the usual telephone apparatus associated with automatic substations.

Fig. 2 shows one of a number of district selector trunks and associated controlling mechanism.

Fig. 3 in the lower left portion shows in schematic form a coordinate sender selector switch by means of which calling lines are associated with idle register senders. In the lower portion of this figure are also shown schematically a number of markers or switch controlling mechanisms together with various connecting devices. In the upper portion of this figure are shown diagrammatically a district switch, a local incoming switch and a final or connector switch.

The line switch 100, sender selector switch 350, district selector switch 380, incoming switch 390 and final switch 395 may be of the general type disclosed in the application of S. B. Williams, Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331. These switches consist in the main of a plurality of horizontal link circuits, and a plurality of sets of vertically and horizontally disposed operating members. The horizontal operat ing members are each individual to a link circuit, and the vertical operating members are apportioned amongst incoming lines and outgoing trunks. The selective operation of a pair of vertical operating members and a particular horizontal operating member determine the selective operation of the switch. Furthermore, the structure of the switch is of such a nature that a plurality of connections from lines to trunks may coexist therethrough.

The sender 310 is of the well known type, comprising relay registers for recording sets of impulses as determined by the operation of a calling subscribers dial, together with certain controlling equipment for automatically supervising the establishment of connections from calling lines to called lines.

The markers or switch controlling mechanisms 320 and 330 are accessible in common to a number of senders as 310. These markers serve to receive certain information from a register sender to which they are attached in sequence to subsequently control the op eration of the several selective switches, such as the district, incoming and final switches to complete the extension of a calling line to a particular called line. hen these respective controlling operations have been completed the markers and the sender are discharged and revert to common use.

Detailed description.

It will be assumed for the purpose of description that the subscriber at station 102 has initiated a call with the purpose of conversing with the subscriber at station 315 whose line is located in the same exchange with that of the calling subscriber. The removal of the receiver by the calling subscriber causes line switch 100 to automatically operate to extend the line 110 to an idle district trunk, such as trunk 150. leading to a district selector switch 380. The connection of line 110 with trunk 150 is accomplished by first causing the operation of the magnet 112 associated with the vertical row of contacts 121. The operation of magnet 112 is immediately followed by the operation of a magnet such as 113, 114. etc., associated with the first idle outgoing trunk. Assuming that trunk 150 is the first idle trunk then magnet 113 individual thereto is operated. lVith magnets 112 and 113 operated a circuit is closed for a horizontal magnet, as magnet 115, associated with the first idle link, as link 116, accommodating line 110 and giving access to trunk 150.

When magnet 115 operates,connectionot line 110 with trunk 150 is completed and vertical magnets 112 and 113 begin to re lease. When these ma nets have released, connection of line 110- with trunk 1550 through link 116, is maintained, since mag net 115 is now held energized through both its windings in series to the grounded sleeve conductor of trunk 150. The sleeve conductor of trunk 150 is temporarily grounder when magnet 113 operates. This ground is also extended by means oi the sleeve conductor of trunk 150, conductor 25%, upper inner and lower inner contacts of relay 203, lower inner armature and back contact of relay 205, conductor 255, to battery through the winding of relay 301, associated with sender selector switch 350. In the manner des .ribed in detail in the above mentioned application of S. B. Williams, Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331, the operation otrelay 301causcs. switch 350 to automatically operate to associate an idle register sender, as 310, with trunk 1530 by means of the group of conductors 351..

When sender selector switch 350 has op erated and a sender has been selected, ground is extended over holding conductor 352 to battery through. the lettwinding of relay 213. The. operation of relay 213 at its left outer armature extends this same ground through the winding of relay. 201 which operates. Relay 201 connects ground through itslower outer armature and front contact thence through the upper normal contacts of relay 206 and the lower outer. contactsot relay 208, winding. of relay 207, to battery through the lower left winding of repeating coil '256. Relay. 20? operates in that circuit. Relay 201 connects ground through its upper outer armature and front Contact to battery through the winding of relay 205which cperates. Relay 205 completes a locking circuit through its winding and locking contact, lower inner contacts of relay 203'to ground. at the upper inner contacts of relay 205. This holding circuit torrelay 205 is maintained until the disruption ofthe con nection. Relay 205 connects ground through its upper inner contacts to the sleeve conductor of trunk 150. By means ofthe, left outer contacts of relay 211 this groundserves to replace the ground which was temporarily applied when magnet 113. operated. It will be obseiwedthat there is associated with the line switch 100 a master-control switch 160 (shown diagraminatically). The opera tion of this master switch is described indetail in the patent to. S. B. lVilliams, here inbetorere ferred to, and is :otsuch a nature as to allow. an appneciable inter between the ,operation and release; of magnet .113. This interval is of suflicientdurationto permit the preceding, described. operations to take place. Consequently. when relay .205

Co d ctors of the extended calling line w nationlo'f the wanted line.

-manner described-Pu detail i operates and placesholding ground on't-runlr 150, magnet 115 is maintained energized to preserve thecon-nection through switch 100.

With relays 205 and 213 operated the circuit above traced for energizing start relay S01 is now broken and this relay releases. The connection through switch 350 is main tained, however, by-the continued energizetion of a magnet such as 303 which is locked throughboth windings in series, through contacts of switch 350 to holding ground supplied by the sender 310.

lVit-h relay 213 operated a circuit is completed from battery at the left inner contacts of relay 212 thence throughthe wind-- of relay 210, lower outer normal contacts of relay 202, resistance 25? to ground at the left inner contacts of relay lay 210 operates and closes an obvious circuit for relay 215 which also operates. W hen interrupter 251 closes its upper contacts subsequent to the operation oi relay 213 battery isconnectedthroughthe le'tt outer. armature and back contact ot relay 212, normal contacts and winding of relay 206, resistance 258, to ground at the armature of relay 213. Relay 2'06 operates in this circuit and immediately closes a locking circuit for itself traceable from battery at the left inner contacts of relay 212, locking contact and winding of relay 206 to ground at the armature of relay 213. Relay 206, by opening its upper normal contacts, breaks the above traced circuit for operating relay 207 and this relay releases. A short interval later, when interrupter 251 closes its lower contacts, battery is connected through the lower inner normal contacts and wind ing of relay 202 to ground at the upper inner contactso'f relay 206. Relay. locks in a circuit traceable from battery the left-inner contacts of relay 21.2, locking contact and winding of relay 202 to ground the armature of relay. 206. A holding circuit for". thetest relay 210 is now completec from ground through resistance 259, lower outer contacts of relay 201, lower outer coutacts of relay 202, winding of relay 210 to battery atthe contacts of relay 212. Test relay 210 under normal conditions is main tained energized in this circuit so long as re lay 201 is operated and the sender 810 is attached to the calling line.

When relay 201 operated the tip and r t-ransterred.-.through contacts of relay and switch 350 to the impulse relay in sends 810. The calling subscriber next in err theline circuitin accordance with t is d V The iinuu lay in the-sender follows these interru and causes the called line designation recorded on the sender: registers. in the n the above mentioned applicat- Vi illiams,

Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331, the record of the office designation is transferred from the sender registers to corresponding registers in the outgoing marker 320, wherein this transferred record is thereupon translated to identify a group of trunks, including trunk 355, leading from district switch 380 to incoming switch 390. The connector device 360 having been operated after sender selector 350 was actuated identifies the particular district switch 380 in which trunk 150 terminates. The connecting device 370 is now selectively operated in accordance with the translated ofiice record in marker 320. With connectors 360 and 370 operated the testing equipment in marker is associated with the links in switch 380 and with the trunks in the group including trunk It will be assumed that link and trunk 355 constitute the first available path for extending the calling line through switch 380. The marker now proceeds to operate the horizontal magnet 356 associated with link 354, the vertical magnet 364 associated with vertical row of contacts 358 having previously operated. Vertical magnet 359 was operated prior to the operation of frame connector 360. Vith vertical magnets 357, 364 and horizontal magnet 356 operated, trunk 150 is connected by means of link to trunk 355. The outgoing marker 320 having completed its function in controlling the operation of switch 380 is discharged, causing the release of connectors 360 and 370 and sender connector 365. The release of these connectors in turn causes the restoration to normal of magnets 359 and 364. The connection through link 354 is now maintained by magnet 356 which is held energized through both its windings in series and thence through contacts of switch 380 to the grounded sleeve conductor of trunk 150. For a detailed description of the manner in which the marker controls the operation of switch 380 reference may be had to the above mentioned application of S. B. lVilliains, Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331, and also to Patent No. 1,600,399, granted September 21. 1926, to W. Carpenter.

lVhen magnet 359 operated, conductor 361 which was grounded by the marker, was extended through an armature of magnet 359 to conductor 363, and thence to battery through the right winding of relay 214. Relay 214 immediately locks in a circuit traceable from battery through its left winding and locking contact to ground at the upper inner contacts of relay 206. This same ground is now extended by means of the locking contact of relay 214, conductor 262, resistance 263, upper outer contacts of relay 206, lower outer armature and back contact a of relay 203, winding of relay 207 to battery through the lower left winding of repeating coil 256. Relay 207 is operated at this time to break the circuit which extends through the left winding of relay 212, the left outer armature and back contact of re lay 209, contacts of relay 207, upper middle contacts of relay 205 and thence to the upper outer back contact of relay 201, so that when relay 201 releases upon the completion of the connection as hereinafter described, relay 212 will not operate.

hen connection was completed through switch 380 as hereinbefore described, and marker 320 was released, the connecting device 37 5 was operated to associate the sender with an idle incoming marker 330. When a marker has been thus associated the numerical portion of the called line designation is transferred from the sender registers to corresponding registers in marker 330 wherein this record is thereupon translated and re sults in the selective operation of incoming switch 390 and final switch 395, whereby an idle link in switch 390, before which trunk 355 appears, is selected, and in addition an idle link in switch 395 giving access to the called line 315 is also selected. At the same time an idle trunk is selected extending between switches 390 and 395 and appearing before the group of links in switch'395 giving access to the called line 315. The application of S. B. Williams, E. S. Gibson, Serial No. 722,215, filed June 25, 1924, Patent No. 1,600,444, granted Sept. 21, 1926, described in detail the manner in which the marker 330 is associated with the register sender and also the manner in which the various connecting devices 371, 372, 373 are selectively operated to control the selective operation of incoming and final switches to complete connections to called lines. Inasmuch as the present invention is concerned mainly with the manner in which message registers are selectively operated, it is believed not to be necessary to give a detailed description of the operations of the connecting devices 371, 372, etc., and switches 390. and 395 which therefore have been described in a general manner.

When connection has been with the called line, which it will be assumed is idle, the sender selector, the sender and marker are thereupon discharged and revert to eommoi use. hen the sender releases holding ground is removed from conductor 352 causing the release of the sender selector and relays 201 and 213. Vith relay 201 released test relay 210 is connected in its operated condition to the tip side of the calling line by means of the upper inner armature and front contact of relay 202 and the uper inner armature and a back contact of 100 to the tip conductor of line 110, through completed contacts engaged by the calling subscrihers switchhook to ground through the ringer coils 105. A parallel circuit also extends through. the lower contact of relay-202 to the ring side of the line. Relay 201 is so adjusted that upondcenergization thereof the upper inner armature and back contact close, before the lower outer armature and front contact disengage. Test relay 210 is thus maintained energized by the. ground at station 102. It will be noted that if the party 'at station 101 "had initiated the call, ringer ground would be disconnected from the tip conductor of trunk 150 by means of condenser 10?. Thus when relay 201 releases after seizure of the called line it would bring about the release of relay .210 providing no unstan-dard conditions exist upon the extended calling-line.

Test relay -210-havingf been applied-to the calling line in an opera-ted condition and the discriminating ground having .been'yencountered relay'210 remains operated after relay 201 releases. Relay 210 in turn maintains relay 215 energized. lVhen interrupter 252 closes next its left contacts'bate tery is connected through the right normal contacts and right winding of relay 208, thence through the upper outer armature and front contact of relay 202 to-gro'und at the armature of relay 201. Relay 208-locks in a circuit traceable from battery at the left inner contact of relay 212, looking contact and right winding of relay 208-to the above traced ground at the armature ofrelay 201.

When interrupter 252 closes its right contacts relays 210 and 213 operate. The 'cir cuit for operating relay 213 maybe traced from battery through the right contacts :of interrupter 252, right outer contacts of relay 208, right'normal contacts and right wind ing of relay 213, conductor 264, upper outer armature and frontcontactof relay 202, to ground at the armatureof' relay201. The circuit for operating relay 216 may be traced from battery through the right contacts of interrupter 252, right outer contacts of relay 208, right outer-armature and front contact of relay 215, right winding of relay 216 to ground. as above traced at the armature of relay 201.. Relay 21 3 looks in a circuit traceable from battery at the left inner contacts of relay 212, locking contact and right winding of re lay 213 to ground as above traced. A locking circuit is also completed for recording relay I 210 which may be traced from-battery through the left winding.- and locking contact thereof, left-outer contacts of relay 211 to groundthroughthe upper inner-contacts ofrelay'205. Relay 216operates to record the fact that the second party on line 110 has initiated-a call.

no oircuitsremain in'this condition until nterrupter again closesdts left contacts whereupon battery is connected through the left contacts of said interrupter, right inner contacts of relay 209, right outer contacts of relay 213 and thence to one terminal of the winding of relay 206 the other terminal of relay 206, also being connected to battery, this relay is now shunted and releases.

Relay 206 in turn causes the release of relay 202,;the latter relay upon its release opening the previously traced operating circuit for test relay 210. The above traced circuits for operating relay 210 it will be remembered were closed through the armatures and frontconjtacts of relay 202. When therefore relay 202 releases as described a substitute circuit is completed for relay 210 which may be traced from battery, at the left inner contacts of relay 212, winding of relay 210, lower normal contacts of relay 202, leftouterarmature and front contact of relay'215,-high resistance 265 to ground. Resistance-265 is of such a Value as to correspond to the-maximum allowable lin.leakage. :R-elay 2110 is so adjusted mechanically and electrically as to be normally unable to remain-energized when its winding is includedin series with resistance 265. Should therefore relay 210 remain operated when connected in series with resistance 265 it is an indication that relay 210 is not correctly adjusted.

l urthern'iore if relay 210 should remain operated in series with resistance 205 ground is connectedthrough the upper outer armature an'dback contact of relay 201, conductor 266, left inner contacts of relay 215 and thence to conductor 26?. Conductor 267 leads to-a selector time alarm circuit 299and the presence of ground on this conductor causes this alarm to function. At theendfof a predetermined interval the continuanceof this ground condition on conductor 267 causes an alarm signal to be operated at a an attendanfis position who can ascertainthe nature of the trouble.

- It will be assumed, however, that test relay 210 is correctlyadjusted and therefore releases when included in series with resistance 265 upon the release of relay 202, When relay 206 releases it opens the locking circuit of relay 21 i. andwhen rela 202 rcleasesitopens-the locking circuit of relay 2.1-8. Relays- 218 and 214c are now in their normal condition. 'lVhen relay 202 releases it'also opens thelocking ci edit of the slow releasing time measure relay 208 which; also begins to release. Supervisory relay 207 is now heldin a circuit traceable from battery through the lower left winding of repeating coil256, winding. of relay 207, lowermost armature andbac'k contact of relay 203, uppen normal contacts of relay 206, lower norl-nal contacts of rel y p201, h n e the ring side of trunk150, through contacts of switch 100, conductor-of the calling line through the calling subscribers substation apparatus, returning thence over the tip side of the calling line through contacts of switch 100, to the tip conductor of trunk 150. thence through the upper inner armature and back contacts of relays 201 and 202, upper outer armature and back contact of relay 203 to ground through the upper left winding of repeating coil 256. The connection is now in a stable condition awaiting the removal of the receiver by the called subscriber.

When the called subscriber removes the receiver from the switchhook the direction of the current in trunks 355 and 150 is reversed causing the operation of the polarized relay 20 1. For the manner in which response by the called subscriber causes the reversal of the direction of the current to operate relay 204 reference may be had to the application of S. B. Williams, Serial No. 596,179, filed October 23, 1922, Patent No. 1,517,331, above referred to.

When interrupter 252-3 closes its right con tacts subsequent to the operation of relay 201, battery is connected through the left normal contacts and left winding of relay 208, lower contact and armature of relay an to ground. Relay 208 closes a locking circuit for itself which may be traced from battery, at the left normal contacts of relay 209, left locking contact and left winding of relay 208, to ground as above traced. A short interval later when interrupter 255 closes its left contacts, battery is connected through the left outer contacts of relay 208, right winding of charging relay 209, to ground through the upper outer armature and b ck contacts of relays 202 and 201. Relay 209 in attracting its left inner armature opens the previously traced locking circuit for relay 208 which becomes deenergizcd. Relay 209 is now locked in a circuit traceable from battery through its locking contact and left winding and thence to ground on the sleeve conductor of trunk 150,- The district trunk and associated apparatus remain in this condition until the termination of conversation.

When the calling and called subscribers have replaced their receivers upon their respective switchhooks, relays 204: and 207 release. The release of relay 204C connects ground through its armature and upper contact, thence through the right middle contacts of relay 209 to conductor 267 which leads to the selector time alarm circuit hereinbefore referred to. The purpose of operating the selector time alarm at this time is to prevent the calling subscriber from maintaining a connection in its busy condition for an indefinite interval subsequent to disconnection by the called subscriber. Upon the release of relay 207 a circuit is also completed from battery at the left inner contacts of relay 212, winding of relay 210, lover outer normal contacts of relay 202, resistance 257, left outer armatures and front contacts of relays 216 and 209, armature and back contact of relay 207, through the upper middle armature and front contact of relay 205, to ground at the armature of relay 201. Relay 210 operates in this circuit. When interrupter 25.1 closes its upper contacts subsequent to the release of relay 207 battery is connected through the left outer armature and back contact of relay 212, thence through the normal contacts and winding of relay 206, conductor 268, resistance 258, left outer armatur and front contacts of relays 216 and 209, armature and back contact of relay 207, upper middle contact of relay 205 to ground at the armature of relay 201. The purpose of operating relay 206 at this time is to make a check test of the calling line to determine the presence or absence of unstandard conditions thereon. When interrupter 251 next closes its lower contacts battery is connected by means of conductor 269 through the lower inner normal contacts and winding of relay 202 and thence to ground at the upper inner contacts of relay 206.

lVith relay 202 operated, test relay 210 is connected in its operated condition, by means of the lower outer armature and front contact of relay 202, to the -ring conductor of trunk 150 and thence by means of contacts in switch 100 to the ring conductor of the calling line. In parallel with this circuit another circuit is traceable through the upper inner armature and front contact of relay 202 to the tip conductor 01' trunk 150 and thence to the tip conductor of the calling line. Since the calling subscriber has replaced his receiver and thus disconnected ground from the tip conductor f the line, should an unstandard condition prevail thereon, such as a false ground or a line leakage greater than that allowable, ground will be extended to maintain test relay 210 in its operated condition. Relay 210 remains energized also holding relay 215 in its operated condition. Thus relays 210, 202 and 206 remain operated as a result of the unstandard condition on the calling line. Under these conditions grounds is connected by means of the upper outer armature and back contact of relay 201, and thence through the left inner contacts of relay 215 to conductor 267 which leads to and causes the selector time alarm circuit to function as hereinbefore described.

Should relay 210 release when it is connected to the tip and ring conductors of the extended calling line as a result of the operation of relay 202, it is an indication that no false ground or unstandard condition exists on the line and that relay 210 llt accents operated correctly in accordance with the discriminating ground as previously described. he release of relay 210 under these conditions causes the release of relay 215. The circuits remain in this condition until interrupter 252 closes its left contacts, whereupon battery is connected through the right normal contacts and right winding of relay 208, thence through the upper outer armature and'front contact of relay 202 to ground at the armature of relay 201. Relay 20S operates in this circuit and closes a locking circuit for itself as previously traced. WVhen interrupter 252 next closes its right contacts, battery is connected through the right outer contacts of relay 208, thence through the right outer armature and back cont-act of-rel'ay 215, the right inner contacts of relay 216, through'the right winding of relay 212 to ground. Re-

lay 212 operates in this circuit and closes a locking circuit foritself which may be traced from battery, through its left winding thence through the right middle contacts of relay 212, armature and back contact of relay 207 ,upper middle armature and front contact of relay 205, to ground at the armature of relay 201.

The-operation of relay 212 at this time by removing battery from the left inner contact of said relay opens the previously traced holding circuits for relays 202 and 206 and these relays now release. In addition relay 212 by means of its right outer contacts connects ground to the sleeve conductor of trunk 150 to replace the holding ground which is later to be removed when relay 205 releases. When interrupter 251closes its upper contact, battery is connected through the left armature and front contact of relay 212, thence through the normal contact and. right winding of relay 211, contacts of'relay 20. to ground through'the upper-na'iddle contacts of relay 205 as previously traced. Relay 211 operates in this circuit and immediately closes a locking circuit for itself which is traceable from battery, through the locking contact and right winding of .relay 211 to ground as above traced. When interrupter 251 neXt closes its lower contacts, battery is connected by means of conductor 269, through the right outer contacts of relay 211, thence through the left inner contacts of relay 211, to ground through the lower winding of relay 203. The operation of relay 203 opens the previously described locking circuit of holding relay 205 and'this relay releases, removing ground from conductor 357 thus causingrelease of switches 880 and 390. Holding ground is, however, maintained=on the sleeve conductor'of trunk 150 by means 'of relay 212 whichrremains locked so long as interrupter 25lanainta-ins its lower contacts in a closedccindition. -With-relay 205 normal and interrupter 251.1nain taini ng its lower contacts closed battery is connected by means of conductor 269, through the right outer contacts ofrelay-211, thence to'conductor 271, through the-lowermost contacts of relay 205, resistance 272, rightouter 'contacts of relay209, right outer armature and frontcontact of relay 216, conductor-273, thence through contacts of switch 100 to conductor 163 to ground throughthe winding of message register 103 which isassociated with substation 102. Message register 10?) operates inthis circuit and causes the-call to be recorded.

After a short interval when interrupter 251 opens its lower contacts, battery for maintaining relays 211 rand 212 operated is disconnected and these relays release. The release of relay 212 removes holding ground from the sleeve conductor of trunk 150 thus bringing about the release of horizontal magnet 115 in the line switch. For a de tailed description of the manner in which the removal of ground from the district trunk causes the release of the selector switches, reference may be had to the patent to S. B. Williams, No. 1,517,331, hereinb forereferred to.

Should the first party, thatis the party at station101,-haveinitiated the call then ringer ground would-be-5missing from the U line conductors of the line when the original party test was made, and relay 216 would remain normal. In this case after disconnection by the calling party no check test is necessary to determinethe absence of ground onthe tip and ring conductors of the tendedline. Sincerelay 216 is normal when interrupter 251 closes. its upper contact subsequent: to the release of relay 207, the cir cuit herein'before traced .for relay 206 is opened at the .outer left contact of relay 216. Consequently neither relay 202 nor relay 215 operate to perform the check test as above described.

Under these conditions as soon as relay 207 releases following disconnection by the calling party, a circuit is immediately closed for relay 212 which may betraced from bat tery-through the left winding of relay 2, normal contacts of relay 216, left outer armature and front contact of relay 209, contacts of relay 20?, upper middle contact of relay 205 to ground at the armature of relay 201. hen interrupter 251 closes its upper contact subsequent to the releasevof relay 207 the circuit hereinbefore described for operating relay 211 is closed and this relay is energized. A' short interval later when interrupter-251 closes its lower contact, relay 203 is operated as previously described. Relay 203 in-turn causes the release of holding relay-205. When relay205 releases alcircuit is-conip'leted for operating the message register associated with substation 101. i This circuit-may betracedfrombattery through the lower contacts of interrupter 251, conductor 269, right outer contacts of relay 211, conductor 2Y1, lowermost contacts of relay 205, resistance 272, right outer contacts of relay 209, right outer armature and back contact of relay 21G, conductor 2'74, and thence through contacts of switch 100 to conductor 1%: to gro'und through the winding of message register 10 i. .Vhen interrupter 251, a short interval later, opens its lower eontaet, relays 212 and 211 release and cause the restoration of the circuit and the selector switches to normal as previously mentioned.

Should the called party fail to answer when the cell at substation 315 is rung, relay i fails to operate. Since relay 20 i is normal when interrupter 253 closes its right contact the circuit previously described for operating relay 208 is opened and relay 208 fails to operate. hen interrupter 253 closes its left contact no operating circuit is found for charging relay 209 and this relay remains normal, thus preventing the operation of the message register since the operating circuit for the message register is opened at the right outer contacts of relay 209. In this case also no check test of the calling line is performed, since no registration is necessary. Consequently, when relay 207 releases following the replacement of the receiver by the calling subscriber, the above-traced circuit for operating relay 210 is opened at the left outer contacts of relay 209 which remains normal when the called subscriber fails to answer. Immediately that relay 207 releases, the circuit for operating relay 212 is closed from battery through the left winding of relay 212, left outer armature and back contact of relay 209, to ground through contacts of relays 20?, 205 and 201. When interrupter 251 closes its upper contacts subsequent to operation of relay 212, the above traced circuit it closed for operating relay 211, and when interrupter l closes its lower contacts the above traced circuit is closed for operating relay 2 3, which causes release of relay 205 and the consequent restoration to normal of the various pieces of apparatus employed in the connection.

i li-at is claimed is:

l. In a telephone exchange system, a calling line, a plurality of subscribers stations on said line, a called line, automatic switching mechanism for extending said calling line to said called line to establish a conversational connection, message registers associated with said calling line and each individual to a subscribers station, means associated with said subscribers stations for placing discriminating test conditions on said calling line, a testing means associated with certain of said automatic switches, said testing means being normally disconnected from the extended calling line, means for operating said testing means, means for applying said testing means in its operated condition to the extended calling line, and means responsive to the presence of a test condition for causing said testing means to select the message register individual to the calling station.

2. in a telephone exchange system, a calling line, a plurality of subscribers stations on said line, a called line, automatic switching mechanism for extending said calling line to said called line to establish a conver sational connection, message registers associated with said calling line and each individual to a subscribers station, means associated with said subscribers stations for placing discrin'iinating test conditions on said calling line, a testing relay associated with one of said automatic switches, said testing relay being normally disconnected from the extended calling line, means for operating said testing relay, means for applying said testing relay in its operated con di ion to the extended calling line, means responsive to the presence of a particular test condition for causing said testing relay to select the message register individual to the calling station, and means effective after the successful completion of a conversational connection for operating the selected mes sage register.

In a telephone exchange system, a calling line, a plurality of subscribers stations on said line, a called line, an automatic switch, a series of selective switches for completing conversatitonal connections between said calling line and said called line, a group of trunks leading from said automatic switch to the first switch in said series, a message register individual to each station, individual operating circuits for said mes sage registers extending through contacts of said automatic switch, a plurality of testing means each individual to a trunk in said group of trunks and normally disconnected therefrom, means responsive to the initiation of a call at any of said stations for operating said automatic switch to seize an idle trunk in said group to extend the calling line to said series of selective switches, means associated with said stations for placing discriminating test conditions on said calling line, means effective subsequent to the seizure of said one of said trunks for op erating the testing means individual thereto, means for applying said testing means in its operated condition to the extended calling line, means responsive to the existence of one of said test conditions for causing said testing means to select the register operating circuit individual to the calling station, and means eflective after the successful co1nple tion of a conversational connection for rendering said selected operating circuit effective.

4-. in a telephone exchange system, a call ing line, a hu'ality of substations on said line, a called line, a line switch, a series of selective switches for establishing conversational connections between said calling line and sa-idcalled line, a group of trunlr's leading "ti-om said line switch to the first switch in said series, a message register For each substation, individual operating circuits for said message registers c .tending through contacts oi": said line sw (ch, a plurality o l testing means each individual to a trunk in said group of trunks and normally disconnected therefrom, means rerponsive to the initiation ot a call at any oi? said stations for ()}-)OI1-ti11,i said automatic switch to seize an idle trunk in said group to extend the calling line to said series of selective switches, n'ieans at one only oi: said substations for placing a discriminating ground potential on one of the calling line conductors, means etlective upon theseizure otsaid one oi said trunks for locally operatingtesting means indiviijlual thereto, means for connecting said testing means in its operated condition to the extended calling line, means responsive to "the existcnce of said ground potential on said conductor t r causing-said testing means to select the register operating circuit individual to the calling substalon, and means ett'ective after thcsuccess'tulcompletion of a conversational connection for rendering said selected operating circuit ofitecti-ve.

5. in a telephone exchange system, a calling line, two subscribers stations on said line, a called line, an :nitomatic switch, a series ct selective switches tor completing conversational connections between said calling line and said called line, agroin') o l trunlcs extending between said automatic switch and said series ot selective switches, n'ieans at one of said stations for placing a discriminating ground 'iotential upon the coijiductors of said calling line, message registers associated with said calling line and each individual to a subscrihefs stat-ion, an operating circuit for said registers norn1al ly arranged tor association with one of said registers, switching means -tor associating said operating circuit with the other oif said reg' iters, a plurality of testing means each individual to a trunk in saidgroup of trunks and normally d isconnectedtherefrom, means responsive to the initiation of a call at either of said stations for operating saidautoniatic switch to extend the calling line to an idle trunk in said group, means eii'cctive subsequent to the seizure of said idle trunk for locally operating the testing means individual thereto, means for connecting said testing means in. its operated condition to the extended calling line, means responsive to saidconnection of said testing means and the existence on the calling line of said discriminating potential for operating said switching means, and means effective after the successful completion of a conversational connection for operating said other of said message registers.

(3. in a telephone e1; hange system, aca lling line, two subscribers stations on said line, a called line, means for extending said calling line to said called line to establish a conversational connection, message registers associated with the incoming end of said calling line and each individual to a subscribers station, means at one of said stations for placing a discriminating test condition upon one conductor of the calling line, testing means normally disconnected from said extended calling line, means for operating said testing means while disconnected from the extended calling line, means for subsequently applying said testing means in its operated condition to the extended calling line, means responsive to said application o't said testin means and to the exist-- ence of said test condition or an unstandard condition on the extended calling line for selecting one of said message registers, means operative upon the successful completion ot a conversational connection for preparing the selected message register for operation, and means eii ective upon the release of the connection and effective only when said line is in a standard condition for operating said selected message register.

'7. In a :telep'honeexchange system, a calling line, two subscribers stations on said line, a called 'line, automatic switches for extending said calling line tosaid called line to establisha conversational connection, mes sage registers associated with said calling line and each individual to a suhscribers 5105 station, means at one of said stations for placing a discriminating ground test conditiou upon the conductors of the calling line whenv a call is initiated at such station, a testing means associated with-certain ottsaid automatic switches responsive to said test condition for causing the selection of the message register corresponding to the calling station, said testing means being normally disconnected from the ext-ended calling line. 5115 means responsive to a partial extension of the calling line for locally operating said testing means, connecting means operative prior to the complete extension of the callmg line for connecting said testing means in ltS operated conditlon to said conductor of said calling line to detect thereon the presence of said testcondition or an unstandard ground condition, means operative upon the successful complete-extension of the calling line to the called line for preparing theselected register for operation, 1119121 118 effective upon the restoration of the calling subscribers receiver to its sw itchhook for reoperating said testing means-and lfor recon- {m necting the same in its operated condition with said calling line to detect the existence thereon of an unstandard condition, and means operative thereafter for operating said selected message register only when said testing means finds that a call has been ini tiated on said line.

8. In a telephone exchange system, a calling line, a plurality of subscribers stations on said line, a called line, message registers associated with said calling line and each individual to a subscribers station, a line switch, a series or selective switches for completing conversational connections between said calling line and. said called line, a group of trunks extending between said line switch and said series of selective switches, means responsive to the removal of the receiver at a calling station for placing a discriminating test condition on the calling line and for operating said line switch to seize an idle trunk in said group of trunks, testing means associated with said idle trunk and normally disconnected therefrom, said testing means being responsive to said test conditions for selecting the message register individual to the calling station, means respons ve to the seizure of said idle trunk and prior to the completion of the connection for locally op erating said testing means, means for connecting said testing means in its operated condition to the extended calling line to de tect thereon the existence 0t said testcondition or an unstandard condition, means for checking the sensitiveness of said testing means attcr connection to the extended calling line, means e'ilective alter the successful establishn'ieut ot' a conversational connection for reop-erating and reconnecting said test ing means in its operated condition to the extended. calling line, and means eiil ective after the release of a connection for operating the selected message register only when said testing means finds that a call has been initiated on said line.

9. In a telephone exchange system, a calling line, two subscribers stations on said line, a called line, trunks for extending said calling line to said called line, message registers associated with the incoming end of said calling line and each imlividual to a subscribers station, means at one of said stations tor placing a discriminating test potential on one of the conductors of the calling line, a plurality of testing means each associated with one of said trunks and normally disconnected there-from, means responsive to the automatic extension of the calling line to one of said trunks for energizing said testing means in a local circuit, means operative thereafter for aplying said testing means in its operated condition to the extended calling line during the establishment of a connection and for reapplying said testing means to the extended calling line subsequent to the restoration of the calling subscribers receiver to its switehhook, means operated by said testing means upon its first application to the extended calling line and responding to said test potential or an unstandard condition of said line for selecting one of said registers, and means operated by said testing means upon its second application to the extended calling line and responding to an unstandard condition thereon for nullitying the selection oi said register.

10. In a telephone exchange system, a call ing line, a plurality of stations on said line, a called line, automatic switching mechanism for extending said calling line to said called line to establish a conversational connection, message registers associated with said calling line and each individual to a station, means associated with said stations for placing a discriminating test condition on said calling lino, testing means normally disconnected from the extended calling line, means for operating said testing means, means for applying said testing means in its operated condition to the extended calling line, means for again applying said testing means to the calling line, means responsive to the presence of a test condition tor causing said testing means to select the message register individual to the calling station, and means for preventing the second application oi said testing means it no discriminating condition is encountered upon the first application.

ll. In a telephone exchange system, a calling line, a plurality oi subscribers stations on'said line, a called line, automatic switching mechanism for extending said calling line to said called line to establish a conversational connection, message registers associated with said calling line and each individual to a subscribers station, means as sociatcd with said stations For placing discriminating test conditions on said calling line, a testing means normally disconnected from the extended calling line, means for operating said testing means, means "tor applying said testing means in its operated condition to the extended calling line, means for again applying said testingmeans to the calling line after the called subscriber answers, means responsive to the presence of a testcondition for causing said testing means to select the message register individual to the calling station, and means for preventing the second application ot said testing means it the. called suliiscriber fails to answer.

In witness whereof, we hereunto subscribe our names this 18th day of August A. I), 1924.

SAMUEL B. lVILLIAMS. EARL S. GIBSON.

till 

